Industrial wastes which are not economical to recycle must be disposed into the environment. Some of these waste materials can be rendered harmless and then disposed in a convenient manner. Other wastes, such as heavy metals, for example, mercury, lead, antimony, arsenic, and radioactive substances, cannot be rendered harmless. Consequently, the disposal of these materials into the environment must be in a manner whereby they are passified, that is, they are localized and remain resistant to delocalization by ecological forces.
Currently, there are two methods for localizing wastes which cannot be decontaminated. One method is sealing the wastes into containers such as metal or plastic drums which are then stored underground or in the ocean. The other method is to incorporate the wastes into a matrix of materials, such as inorganic cements and polymers while in their fluid or molten state followed by solidification. The high viscosity of the molten plastics generally limited the quantity of waste that could be loaded into the plastic matrix. The incorporation method was limited also by the inability of the matrix to isolate the waste from the environment. Highly loaded matrices, that is, over 30 percent loadings, which were exposed to the environment were unsatisfactory because of leaching. Both of these methods present two critical disadvantages. One disadvantage is the ultimate tendency of the wastes to become delocalized, and the other is the increasing expense of providing systems with increasing assurance of long-term stability.